JPH0339366B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arc extinguishing mechanism for switches that switch on and off current, such as electromagnetic contactors, wiring switches, and disconnectors.

A conventional electromagnetic contactor is shown in FIG. In the figure, 1 is a mounting base made of plastic, and 2 is a fixed core made of laminated silicon steel plates. 3 is a movable core made of laminated silicon steel plates like the fixed core 2. Reference numeral 4 denotes an operating coil that provides a driving force to attract the movable core 3 and the fixed core 2 against a tripping spring (not shown). 5 is a cross bar made of plastic and having a square window, which holds the movable iron core 3 at its lower end. 6 is a movable contact inserted and held in a corner window of the cross bar 5, and 6A is a movable contact joined to one end of the movable contact 6. 7
is a push spring that presses the movable contactor 6. 8 is a fixed contact provided opposite to the movable contact 6;
8A is a fixed contact joined to one end of the fixed contact 8, and is configured to be able to come into contact with and separate from the movable contact 6A. 8C is a terminal portion provided at the other end of the fixed contact 8, and when the fixed contact 8A and the movable contact 6A are in contact, current is passed from the fixed contact 8 to the movable contact 6. 9 is a terminal screw for connecting the electromagnetic contactor main body to an external circuit, 10 is a base for attaching the fixed contact 8, 11 is a cover that covers the top surface of the electromagnetic contactor, and 12 is a fixed contact 8A and a movable contact 6.
This shows the arc that occurs when A and A are separated. Reference numeral 13 denotes a magnetic metal arc extinguishing plate for extinguishing the arc 12. The electromagnetic contactor shown in the figure is symmetrical, so only the right cross section is shown. FIG. 2 shows an enlarged perspective view of the metal arc-extinguishing plate 13, the fixed contact 8, and the fixed contact 8A.

In the switch configured as described above, when the operating coil 4 is demagnetized, the movable core 3 is separated from the fixed core 2 by a tripping spring (not shown), and the crossbar 5 is placed in the state shown in FIG. , the fixed contact 8A and the movable contact 6A are separated. At this time, an arc 12 is generated between the fixed contact 8A and the movable contact 6A because they are separated from the energized state, but at the current zero point, the arc 12 is extinguished by the metal arc extinguishing plate 13, and the current stops. or be cut off. The extinguishing process of the arc 12 will be explained using FIG. 3. FIG. 3 shows a side view of the arc extinguishing chamber. The arc 12 generated between the movable contact 6A and the fixed contact 8A is attracted to the magnetic metal arc extinguishing plate 13 and is elongated like an arc 12A. When the arc 12 is stretched, the arc voltage increases, so dielectric breakdown occurs between the fixed contact 8 and the metal arc extinguishing plate 13 and between the metal arc extinguishing plate 13 and the movable contact 6A, and the arc 12A
is divided into two arcs 12B and 12C, and these two arcs 12B and 12C are extinguished at the current zero point.

In the conventional electromagnetic contactor as described above, the arc voltage is low because the extension of the arc 12 is restricted by the presence of the metal arc-extinguishing plate 13. Therefore, dielectric breakdown is less likely to occur between the fixed contact 8 and the metal arc-extinguishing plate 13 and between the metal arc-extinguishing plate 13 and the movable contact 6A, and the arc 12 is less likely to be divided into two arcs 12B and 12C. It was. For this reason, excellent fiber cutting performance could not be obtained. Furthermore, electric field concentration of the metal arc-extinguishing plate 13 occurs and an arc 12C is generated at the tip of the metal arc-extinguishing plate 13, which has poor thermal conductivity, which is one of the main causes of poor cutting performance.

A power switch which improves the above-mentioned drawbacks and improves insulation performance has been previously invented, and FIG. 4 shows a perspective view of the metal arc-extinguishing plate 13 of the prior invention. In the figure,
13A is a U-shaped protrusion provided at the end of the metal arc-extinguishing plate 13 facing the fixed contact 8, and a hole 13B for gas circulation is provided in the upper part of the protrusion 13A. A side view of the arc extinguishing chamber using this metal arc extinguishing plate 13 is shown in Figure 5.
As shown in FIG. As shown in FIG. 5, the arc 12 generated between the fixed contact 8A and the movable contact 6A is attracted to the magnetic metal arc-extinguishing plate 13, causing an arc 12D.
Through this state, the arc 12E is extended along the U-shaped protrusion 13A of the metal arc-extinguishing plate 13, and the arced gas containing electrons and ionized anions passes through the gas flow hole 13B. For this reason hole 1
Dielectric breakdown occurs near 3B, and the arc 12E splits into two arcs 12F and 12G, as shown in Figure 6.
divided into Arc 12 is two arcs 12
When divided into F and 12G, U of the metal arc extinguishing plate 13
Since the current flows through the letter-shaped protrusion 13A, the arc 12
F and arc 12G are driven by the magnetic field created by the current and move to arc 12H and arc 12I, and when the current reaches zero point, it is extinguished and the current is interrupted.

In the electromagnetic contactor of the prior invention as described above, the hole 13 at the top of the U-shaped protrusion 13A of the metal arc extinguishing plate 13
The arc 12 is broken due to dielectric breakdown near B, and the arc 12 is broken by the magnetic field created by the current flowing through the U-shaped protrusion 13A of the metal arc extinguishing plate 13.
G and 12F run on the metal arc-extinguishing plate 13 at high speed. Furthermore, as shown in FIG.
Because electric field concentration occurs and arcing does not occur at the tip, which has poor thermal conductivity, extremely excellent shear cutting performance can be obtained. Also, the hole 13 for gas distribution
Due to the presence of B, dielectric breakdown easily occurs near this hole 13B, so the arc time is shortened.

However, when the electromagnetic switch of the prior invention cuts or breaks a small current of high voltage, it has a drawback that the legs of the arc tend to stick together in the hole for gas flow. Fig. 7 shows a case where the leg of one arc 12G of the two divided arcs 12G and 12F is formed above the gas circulation hole 13B, and Fig. 8 shows the metal arc extinguished in this case. It is a diagram of the plate 13 viewed from the side of the space where the arc occurred. arc 1
A current flows into the metal arc extinguishing plate 13 from 2F, but as shown by the broken line in FIG. 7, this current is divided into both sides of the gas flow hole 13B and flows into the legs of the arc 12G. This inflow current is denoted by I ₁ and I ₂ .
The magnetic field acting on the arc 12G is dominated by the magnetic field created by the current flowing near the legs of the arc 12G. As shown in Figure 8, the current I ₁ is arc 12G
The magnetic field acting on the arc 12G is H ₁ , and the magnetic field acting on the arc 12G due to the current I ₂ is H ₂ , and their combined magnetic field H acts on the arc 12G. Therefore, arc 12G
Since it receives a downward driving force, it does not travel upward and has the disadvantage that its shearing performance cannot be improved.

This invention was made in order to eliminate the above-mentioned drawbacks, and a U-shaped protrusion is provided at one end of the metal arc-extinguishing plate facing the fixed contact and facing the separation space between the fixed contact and the movable contact. By providing a protrusion and providing a groove with a predetermined depth from the other end of the metal arc-extinguishing plate,
The object of this invention is to obtain a power switch that can smoothly switch on and off small currents at high voltages.

FIG. 9 shows the shape of a metal arc-extinguishing plate showing an embodiment of the present invention. In the figure, 13C is metal arc extinguishing plate 1
This is a notch groove provided at a predetermined depth from the end opposite to the U-shaped protrusion 13A provided at one end of 3. This cutout groove is cut to a position closer to the fixed contact 8 than the reference position based on the position of the back surface of the movable contact 6 (the surface on the side to which the movable contact 6A is not bonded). This arrangement makes it easier for the arced gas to flow in the side direction of the movable contact 6 through the cutout groove 13C, so that dielectric breakdown occurs at the shortest distance between the movable contact 6 and the metal arc-extinguishing plate 13. , the arc becomes more likely to be divided. In this embodiment, the current flowing from the arc 12F flows upward and flows into the arc 12G. Therefore, the arc 12G is driven upward along the groove 13C, reaches a current zero point while traveling, and is sheared. Since the arc 12G reaches the current zero point while traveling in this way, the temperature rise at the foot of the arc 12G is suppressed, and the positive column is rapidly deionized, so that the small current of high voltage can be interrupted or disconnected. It also has excellent performance against

It goes without saying that the present invention can provide similar effects to those described above even when the fixed contact is U-shaped. Further, in the above embodiment, the present invention is applied to a switch whose contacts are opened and closed by a magnet, that is, an electromagnetic contactor, but it can also be applied to other power switches such as wiring switches and disconnectors.

As described above, a fixed contact and a movable contact having a fixed contact and a movable contact that can be brought into contact and separated, and a magnetic metal that is perpendicular to the joining surface of the fixed contact of the fixed contact and facing the joining part of both contacts. In a power switch having an arc-extinguishing plate, a U-shaped protrusion is provided at one end of the metal arc-extinguishing plate facing the fixed contact, the protrusion facing the separation space between the two contacts, and the metal arc-extinguishing plate By providing a groove with a predetermined depth from the other end, it is possible to obtain a power switch with excellent performance in breaking small currents at high voltages.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view showing a conventional electromagnetic contactor, Fig. 2 is an enlarged perspective view of the main part of Fig. 1, and Fig. 3 is an eraser for explaining the operation of the main part of the conventional electromagnetic contactor. FIG. 4 is an enlarged perspective view of essential parts showing an embodiment of the prior invention; FIGS. 5, 6, and 7 are side views of the arc chamber showing the operation of the prior invention; FIG. 8 is an explanatory view seen from the front of the arc-extinguishing plate for explaining the operation of the prior invention, and FIG. 9 is an enlarged perspective view of essential parts showing one embodiment of the present invention. In the figure, 6 is a movable contact, 6A is a movable contact, 8 is a fixed contact, 8A is a fixed contact, 13 is a metal arc-extinguishing plate, 13A is a U-shaped projection provided on the metal arc-extinguishing plate 13, and 13C is a It's a groove. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A fixed contact, a fixed contact connected to the fixed contact, a movable contact, a movable contact connected to the movable contact and capable of coming into contact with and separating from the fixed contact, and the above of the fixed contact. In a power switch having a magnetic metal arc-extinguishing plate perpendicular to the joint surface of the fixed contact and facing the joint part of both the contacts, the fixed contact is attached to one end of the metal arc-extinguishing plate facing the fixed contact. A U-shaped protrusion is provided that faces the separation space between the contact and the movable contact,
A power switch characterized in that a cutout groove is provided from the other end of the metal arc-extinguishing plate. 2. The power switch according to claim 1, wherein the cutout groove is cut to a position closer to the fixed contact than the surface of the movable contact to which the movable contact is not bonded.